If those stupid ass thieves would take half of the energy they put into trying to get your car and put it into getting a job and saving their own $$$ they could have had a GSR of their own by now.
What kind of property do you live on? Is there a garage? Can you pay extra for one? Can you invest in a mobile shelter? How about a dog in the yard? any chance at that? Does a neighbor have space in a garage that you can use? How about a shed? Got one of those?
These guys are obviously not pro's. Like Dave said. They would have made off w/it the 1st time if so. I think they are using your car for practice, and look after 6 tries they still suck at it. I think it is more of a determination for them this point so they don't feel defeated.